Not sure if it perfectly fits your criteria, but you could find it interestingly related anyway.

In the 1887<sup>\*</sup> illustrated sci-fi story *La Guerre au 20ème siècle* ("War in the 20th Century") by Albert Robida, an unidentified army tries to use land mines and shells loaded with various diseases against the French army. All of this is designed by doctors, chemists, and engineers. 

However, the French destroy the "miasma reservoir" where the diseases are stored, before the mines and shells are used against them. As a consequence, the diseases leak and spread among the enemy. The mix of diseases creates a new, unknown disease called the "fièvre molineuse", certainly killing thousands of civilians and soldiers (but sparing the French). 

At the end of the chapter, it is mentioned that doctors across Europe "grow" this new disease – to weaponize it I'd assume, as medical ethics does not seem to be a concern in this fictional universe.

Below is an illustration from the book, representing the inside of a fortified place where doctors, chemists, and engineers develop their biological warfare plan. We see a sort of small lab on the right, and some tanks just under the large cannon, labelled with various disease names, including measles, dysentery, typhus, and smallpox (later, the text mentions additional diseases like yellow fever and... odontalgia):

[![Interior view of the fort, p.16][1]][1]

Here is an illustration of the "réservoir à miasmes". In front of it, there are some doctors and engineers, manipulating a couple of flasks or vials:

[![Copy of p.17 of the story, where the "miasma reservoir" is illustrated, with 6 men in front of it - presumably 5 doctors and 1 soldier][2]][2]

And here is an illustration of the reservoir leaking after the French attack, with some smoke or vapor escaping from it, possibly some liquid too:

[![Copy of p.17 of the story, where we see the reservoir leaking after an explosion, with some smoke or vapor escaping from it, and possibly some liquid too. A dozen of soldiers around panic and fall on the ground.][3]][3]

It seems there's a 1998 translation of the story in English, but I couldn't find it online. You can find the original story in French on Gallica at the following address, with higher resolution images than those I shared above: https://gallica.bnf.fr/ark:/12148/bpt6k3120885  . The chapter where the weaponized diseases appear is pp.16-20. 

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<sup>*</sup> The [Wikipedia article on this story][4] mentions 1883 as a first publication date, but I did not verify the information. On the other hand, Gallica mentions 1887.


  [1]: https://i.sstatic.net/ho4JM.jpg
  [2]: https://i.sstatic.net/kGfMY.jpg
  [3]: https://i.sstatic.net/ft4MI.jpg
  [4]: https://en.wikipedia.org/wiki/War_in_the_20th_Century